Single-phase commutator motor



Oct. 30, 1923.

WITNESSES:

Wdmx/t 1,472,172 R. E. HE -LLMUND SINGLE PHASE COMMUTATOR MOTOR ets-Sheet 1 8 9 l0 1/ /2 l3 firm-T. Fawa "d I O O Q Rona/I79 O O O 0 O 0 5m? Reverse 0 I Q Q VENTOR IN E ado/f5 Heflmwrd.

ATTORNEY Patented (lot. 30, 1923.

entree STATES PATENT orator..-

RUDOLF E. HELLJMUND, OF SWISSVALE, PENNSYLVANIA, ASSIGNOR TU WESTING- HOUSE El EC'IRIC AND MANUFACTURING COMPANY, A CORPORATION 0F PENN- SYLVANIA.

SINGLE-PHASE COMMUTATOR MOTOR.

Application filed January 26, 1917.

To (17! whom it may concern Be it known that I, RnooLr ll. HELIr MUNI), a subject of the German- Emperor, and a resident of Swissvale, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Im rovement in Single-Phase (ommutator i otors, of which the following is a specification.

My invention relates to alternating-current commutator motors and particularly to motors that are adapted to operate either assubstantially constant-speed or as adjustable-speed motors.

The object of my invention is to provide a control system for motors of the character designated which shall permit the motors to be started and operated in either direction and produce particularly desirable commutating conditions and general operating characteristics with a minimum of control apparatus.

it has heretofore been proposed to start motors of the above-indicated type as repulsion motors and to establish an auxiliary armature circuit after the motor reaches substantially synchronous speed. My invention provides a control system for a motor of the character designated in which the magnetic axis of the armature is disposed at an angle relative to the main stator magnetic axis for starting and is brought into alinement with the magnetic "axis of the stator winding for running positions.

Figs. 1V and 2 of the accompanying drawings illustrate my invention as applied to single-phase commutator motors having inductively-fed armature fcircuits. Fig. 3 illustrates a device for automatically changing the motor connections when certain operating conditions of the motor are reached. Figs. 4, 6, 9, 11, 13, 15, 17, 19, 21 and the corresponding switch-sequence chart-s'shown in Figs. 5. 7, 10, 12, 14, 16, 18, 20, and 22, illustrate the application of my invention to motors of the doubly-fed type. Fig. 8 illustrates another'application of my invention to motors of the doubly-fed type.

Fig. 1 of the drawings illustrates a motor 1 comprising a stator-field winding 2, an armature 3, and a plurality of armature brushes 4. 5, 6, and 7, and a plurality of control switches 8, 9, 10. 11, and 12 for governing the operation of the motor 1. The motor is adapted to be started into opera- Serial No. 144,663.

tion by establishing-a magnetizing circuit for the stator-field Winding 2 from the-supply-circuit conductors 18 and 19 and by completing a local circuit for the pair of brushes 4 and 5 of the armature 8. 'lhc,

switches 8 and 9 are closed to establish the stator magnetic field, the magnetic axis of which is coincident with the axis of the stator winding 2, and the switch 10 is elosd to establish an armature circuit which gularly disposed relative circuit of the stator.

With the connections established as shown, the motor will start as a. repulsion motor and will have a starting torque which is very large and is dependent upon the angular relation between the magnetic axis of the winding 2 and that of the armature ii. When the motor reaches a predetermined speed, the switches 11 and 12 are closed to establish an auxiliary armature circuit, the magnetic axis of which is symmetrically placed relative .to the magnetic axis of the stator winding 2 and the brushes 4 and 5 and which, if combined with the magnetic flux produced by the current flowing in the circuit for the brushes 4 and 5, will pro duce a resultant armature magnetic flux the axis of which is in alinement with/the axis of the field winding 2. The motor, as now connected. is of the armature-excited type and will operate-at substantially constant speed. The speed may be changed, however, by changing the impedance of the external brush circuits or by shifting the position of the brushes.

Fig. 2 shows a modified form of the motor which is provided witlrthree brushes 5, 6, and 7 instead of the form described in connection with Fig. 1. The brush 7 is made adjustable relative to the other two and is adapted to be shifted to the position shown in dotted outline to establish a magnetic axis for the armature at an angle to the stator magnetic axis for starting the motor. The brush 7 is first moved to the position shown in dotted outline. The switches R and 9 are then closed to establish a magnetizing cireuit for the stator winding, and the switc 10 is closed to establish an external armatnre circuit between the brushes 5 and 7. Since the magnetic axis of the armature is substantially in alinement with the brushes externally connected, it will lie at an angle to the magnetic ill"? relative to the stator magnetic axis and will give the same starting cllaracteristics that were secured in the motor illustrated in Fig. After the motor reaches a predetermined operating speed, the brush 7 is shifted to the position shown in solid outline. Vl ith the brush 7 in the running position, the magnetic axis of the armature and that of the stator are substantially coincident, and the motor is armature excited.

A centrifugal device, which automatically shifts the brush to the running position when the motor reaches a certain speed. is diagrammatically illustrated in Fig. 3, and comprises a motor armature 3 that is adapted to rotate a plurality of weights 20. an arm 21, which is pivoted on the motor shaft and is moved in accordance with the position oi the weights 20. and a safety device for preventing the closure 01 switches 8 and 9 when the arm 21 is in other than the ofi position. The arm 21 is provided with a brush 7, at one end. that is adapted to be moved by the arm 21 and a contact member 23, at the other end, that co-operates with stationary contact member 24 to close the switch designated by 12 in Fig. 2. Motion is transmitted from the weights 20 to the arm 2i by means of a collar 25, a lever 26 and a link 27. As the motor-armature speed increases, the weights 20 are thrown outwardly and the brush 7 is moved from the position shown in solid outline to that shown in dotted outline. When the brush 7 reaches its final operating position, the switch 12 is closed by the engagement of the contact members 23 and 24. The safety device 22 comprises an arm which operates the switches 8 and 9 by its movement and has a latch 28 secured to one end thereof. When the weights are thrown outwardly. a pin :29 is raised and, if an attempt be made to close the switches 8 and 9, with the pin in this position, the pin will engage the latch 28 and prevent the closure of the switches 8 and 9. It, however, it is desired to open the switches 8 and 9 after the motor is operat ing. the latch swings back and allows the switches to beopened. A spring 30 maintains the latch in an upright position. The motor is thus protected from injuries incident to closing the switches 8 and 9 when the brush 7 is in the neutral or operating position. If it is desired to start the motor in a different direction, the link 27 may be connccted to a point on the other side of the pivotal center of the arm 21. The brush 7 must ocupy a starting position on the other side of the running position or substantially diametrically opposite from the brush 6 but must again be moved to the position shown in dotted outline when the motor is operating.

I desire it to he distinctly understood that the automatic control apparatus shown in Fig. 3 is merely illustrative in character and may be radically modified in details, ,in actual practice, without departing from the spirit and scope of my invention.

Fig. l illustrates a double-fed motor 1 in which the field winding 2 is supplied trom a portion 31 ot a transformer winding, and the armature 3 is supplied from av portion 32 of the transformer winding. Fig. 5 is a chart showing the sequence oi operation of the switches for the motor circuit illustrated in Fig. i. For starting in one direction. the switches 10, 11. and 1a are closed which cstablishcs a circuit for the licld winding 52 and a circuit for the armature winding between the brushes i. and 5 from the se 'iaralc portions 31 and 32 of the translbrmer. The magnetic axis of the armature circuit be tween the brushes l and 5 is positioned a an angle relative to the magnetic axis ot the field 2 and, therefore, the motor will have a large starting torque. For the running position, the switches '12 and 13 are closed which establishes an armature-exciting circuit between the short-circuited brushes 4 and 7 and 5 and 6. This again shifts the magnetic axis of the armature wi'mlins' into alinement with the magnetic axis of the stator winding, as in the t "anslormcr mot on: shown in Fig. 1. and Fig. 2. The motor shown in Fig. t may be started in the opposite direction by closing the armature switches 12 and 13 instead of switches i l and 11 for the starting position. The dotted line shown is for a reverse doubl vl'cd connection or, in other words. for a. connection wherein the voltage impressed upon the inducing field winding exceeds that impress d upon the armature and magnetizing field windings.

Fig. (3 illustrates a motor simi ar to that shown in Fig. 4 except that the armature is provided with three sets of brushes instead of tour. For this motor. the armature circuit for starting is established from the brush 7 to the brush 5 by closing switches F am: 10. The switch 11 is closed after the motor reaches operating speed. Finch a system or connections-as that shown in Fig. 6 will not yield so large a starting torque as is pro vidcd by the connections shown in Fig. i but will reduce the number of switches required to control the operation of the motor since, in this case. only Your switches are. re quired. whereas. in the corrcspondiug case illustrated in Fig. 4. seven switches are required. The brush 7 may be shifted by a device similar to that shown in Fig. 3 to provide a. greater number ot ell'ective urmrr ture turns for starting if it is desired to sccure a large starting torque.

Fig. 8 shows a motor in which the brush 7 is adapted to be shifted out of alinemeni with the stator field and in which the brushes .3 and (i are permanent l v shorl circuil ed by an lie 'erating position. the

inductive reactor 33 which is adapted to inductively oppose the flow of exciting current between the .brushes 5 and 6 but is substantially non-inductive, as regards the flow of a working current from the brush 7 through the armature and the brushcs-5 and 6 to the supply-circuit transformer 32. The direction of operation in'this case is dependent of the brush 4 in startwill have a small starting torque but will have substantially constant-- relation across the For starting, an

a motor so connected is dependent upon whether the switch 10 or the switch 11 is fi d first closed. After operating speed is reached, the switches 8, 9, 10, 11 and 13 are closed and the switch 12 is opened. This system of acceleration provides very good commutating conditions and smooth acceleration, with a. large starting torque.

Fig. 15 discloses an application of the principles discussed in connection with Fig. 13, except that four sets of brushes are emloyed. p shows a connection similar to that in Fig. 8 except that a short-circuitingconnection is established acrom the brushes 5 and 6 by a switch 12 after the motor has reached full speed.

The circuit arrangements shown in Fig.

15} employ two reactors instead of the one discussed in previous figures. A circuit is first established through the reactors and the armature in series-circuit relation across the supply-circuit conductors. For full opreactors are non-inductive relative to the flow of load current there through but inductively oppose the flow of magnetizing current. In this connection, it may, at times, be desirable to wind the reactors upon a common core in order that, for starting conditions, the two portions of the .uit is established through the separate reactors may be made substantially non-inductive relative to the flow of load current at starting. Fig. 21 illustrates a motor which is adapted to start as a shortcircuited'repulsion motor and to have inductive reactors inserted in the circuit for the armature magnetizing current during operation. Either the switch 10 or 11 is adapted to be closed in the starting position for the armature 3 in accordance with the desired direction of operation. This establishes a magnetic circuit for the armature 3 the axis of which is in angular relation relative t the stator-field magnetic circuit a brought into alinement with the-magmas axis of the stator 'fi'eld winding by closing the switches 14 and 15. This motor has the same operating characteristics as that shown in ft will be understood that, whi e the auto matic controlling device shown in Fig. 3 is applied to the circuit arrangement. shown in ig. 2, my invention contemplates the application of such automatic controlling device, or its equivalent, to effect any or all of the adjustments involved in any of the other systems hereinbefore described.

Although that only such limitations shall be imposed as are indicated in the appended claims.

claim as my invention:

1. The combination with a dynamo-electric machine having a commutator comprising a plurality of brushes, and a -magnet winding, of means dependent upon the operation of said machine for automaticallychanging the position of one of said brushes and maintaining the same in engagement with the commutator cylinder, auxiliary contact members adapted to be closed for a certain brush, and interlocking means for prevent magnet winding, of means co certain positions.

3. A single-phase commutator motor having a field windin an armature winding, a commutator cylinder 'for "said armature winding. :1 pairof' brushes bearing upon said commutator cylinder and disposed substantially symmetrically with respect to the I have described my invention 7 y as applied to only a few of the f axis of said tield winding, a reactor adaptcd to be connected to said brushes, said reactor having a middap. and an adjustable brush- :neans bearing upon said commutator cylinder and adapted to be electrically associated with said mid-tap for cstahlishing' a result ant armature field either at an angle to said field winding axis or in alinement therewith, according; to the position of adjust.- ment of said brush-means.

4. A single-phase commutator motor having a tield winding, an armature winding, a commutator cylinder fon said armature winding, a pair of brushes bearing, upon said commutator cylinder and disposed substantially symmetrically with respect to the axis of said field winding, a reactor conncctine said lrushes said reactor having a mid-tap, brush-means for establishing an unsymmetrical path through said armature winding from said mid-tap to a point out o alinement with said field axis, and bruslr means for establishinc a symmetrical path through said armature winding from said mid-tap, said last-mentioned path being,

symmetrical and arranged parallel with respect to said field axis.

5. A single-phase commutator motor ha\'- ing a field winding, an armature winding, a commutator cylinder for said armature winding, a pair of brushes bearing upon said commutator cylinder and disposed substantially symmetrically with respect to the axis of said field winding, close-t.-ircuitin; means for said brushes, an adjustable brushmeans bearing upon said commutator cylinder and electrically associated with one of said first-mentione brushes for establishin;, a resultant armature field either at an angle to said field winding axis or in alinement therewith, according to the position of adjustment of said brush-means, and automatic means for closing said close-circuiting means when said brush-means is in its second-mentioned position of adjustment.

In testimony whereof I have hereunto subscribed my name this 20th day of J anuary, 1917.

RUDOLF E. HELLMUND. 

